UPGRADING OF PYRENEAN AND VOLMALENCO TALCS

UPGRADING OF PYRENEAN AND VOLMALENCO TALCS

Od 1988-03-01
do 1990-04-30

Dane projektu

Całkowity koszt:

Niedostępne

Wkład UE:

Niedostępne

Kraj koordynujący:

Italy

Topic(s):

System finansowania:

CSC - Cost-sharing contracts

Cel

THE RESEARCH IS INTENTED TO IMPROVE THE PROCEDURES FOR THE UPGRADING OF FRENCH, SPANISH AND ITALIAN TALCS IN ORDER TO EXTEND THE USE OF TALCS AND THE ASSOCIATED ORES IN THE PRODUCTION OF CERAMICS FOR ADVANCED TECHNOLOGIES, IN THE PRODUCTION OF PAPER AND PLASTIC PRODUCTS, AND ANTI-CORROSION PAINTS. THE COMMUNITY IS CURRENTLY IMPORTING 200000 TONNES PER YEAR OF TALCS TREATED BY FLOTATION WHICH ORIGINATE IN ORES SIMILAR TO THOSE IN VALMALENCO. The use of selective flotation with the mechanical dissolution of mineral samples has provided an economical method for the exploitation of talc deposites. Selective flotation used with foaming agents based on the natural hydrophobicity of talc has enabled a 3-phase separation of all samples which depends on the impurities present and the function of the treated product. It has been shown that the mechanical processes of either crushing the sample or crushing followed by grinding in a ceramic grinder enables sufficient liberation of the mineral species. Several rewashing processes are necessary to achieve a quality product.

Research has been carried out into the direct beneficiation of talcs either by wet micronizing or heat treatment. The possibility of obtaining talc rich or chlorite rich concentrates with low amounts of impurities (carbonates, iron minerals) has been studied. The separation processes were froth flotation, hydrocycloning or magnetic separation. Research into the direct beneficiation of pyrennean talc ores involved 3 different samples a talc rich ore, a chlorite rich ore and a very pure indian talc used as a reference.These studies increased knowledge of wet treatments and as a result, lead to different new investments in the plant involving:a unit for designing slurries for paper coating (7500 t/year);a wet microgrinding unit;a drying unit for treating the products obtained after wet treatments.

Work on the beneficiation of pyrennean talc ores by flotation and magnetic separation involved magnetic separation (either high wet intensity of very high field obtained by a superconducting coil) and flotation.Tests revealed that chlorite is not separated either by high field or very high field magnetic separation. This means that magnetic separation is not suitable for enriching the ores.Selective flotation using only a frother (natural hydrophobicity of talc) lead to concentrates with more than 90% talc content (recleaning of the floated products may be necessary).3 different processes have been tested for separating chlorite from dolomite:size classification by a cyclone;direct flotation of dolomite using fatty acids as collectors;direct flotation of chlorite using cationic collectors.As a result of these studies, a semiindustrial scale flotation plant (2500 t/year) was built for obtaining talc concentrates.

With respect to the flotation of talc ores from Valmalenco, method was developed for obtaining the real mineralogical composition of a very complex ore. The approach required the combination of very modern analysis methods and statistical m ethods such as principal component analysis.Talc recovery was around 30% whilst the chlorite and carbonates recovery was 22% and 4% respectively. The talc and chlorite recovery could be increased up to 68% and 44% respectively by floating the ore using isoamylalcohol as a collector.1. PYRENEAN TALCS :